basically in chemical equilibrium there must be some amount of stoichiometric equivalent that allows me to measure the exact amount of NaCO3 + H20 in the solution so that I get exactly one molecule of NaCO3 for every one molecule of H2O equal to (=) one molecule of NaOH and one molecule Carbonic Acid H2CO3. I would think the measurement would be in grams but the exact amount will not be as close as I think because of the famous Avogardo 6.023 x 10^23 needs some form of coefficient for the conversion of the exact amount of each atom in each molecule. Ionic or polyatomic...See Avogadro's Proof...